Ignition trip for oil burner controls



July 31, 1951 P, CHELL 2,562,438

I IGNITION TRIP FOR OIL BURNER CONTROLS Filed Sept. 18, 1947 2 Sheets-Sheet 1 Q g M LW Q II ".1, I

ig 1 q, *0 W *3 \i NVE/VTOR- I L?) 76W 9 2% P. SCHELL IGNITION TRIP FOR OIL BURNER CONTROLS July 31, 1951 2 Sheets-Sheet? Filed Sept. 18,. 1947 IN V EN TOR. BYPQLLL fiched m 7 3 Patented July 31, 1951 IGNITION TRIP FOR OIL BURNER CONTROLS Paul Schell, Elkhart, Ind., assignmto Penn Electric Switch (30., Goshen, Ind., a corporation of Iowa,

Application September 18, 1947, Serial No. 774,818 2 Claims. (Cl. 200-88) This invention relates to an ignition trip for anoil burner control apparatus of the character shown in Shaw Patent No. 2,162,126 issued June 13, 1939; 1

One object of the-present invention is to eliminate an electrical ignition trip mechanism of that patent and substitute in place thereof a simplified mechanical means to trip the ignition switch to the open position in the event of establishment of combustion at the burner.

Another object is to provide a burner control wherein relay mechanism is arranged so that the ignition switch remains open when the relay is off thus preventing the motor of the burner when coasting to a stop and thereby generating a current after the burner is shut down, from energizing the ignition mechanism which would ignite any gases remaining in the furnace after the relay has been lie-energized, my arrangement being thereby operable to permit such gases to be cleared from the furnace by the natural draft after shutdown of the burner.

Still another object is to provide a burner motor relay having associated with it an ignition switch and mechanism for operating the ignition switch partially by the armature of the relay and partially by a combustion responsive element, the relay effecting closure of the ignition switch at the time the burner motor is energized and the combustion responsive element causing the ignition switch to be mechanically unlatched in relation to the relay armature so that it returns to its normally open position yet is in such position that when the relay subsequently drops out the ignition switch is again conditioned for subsequent closure of the ignition switch upon pull-in of the relay.

A further object is to provide a burner control mechanism including an ignition circuit in which there is an ignition switch so controlled that it may be closed by energization of the relay, opened by movement of the combustion switch to the position it assumes as a result of combustion establishment and maintained open instead of reclosing when the relay coil is deenergized.

Still a further object is to provide a simple essary additional wiring and additional contacts for controlling the circuit of the ignition trip coil. I

With these and other objects in view, my invention consists in the construction, arrangement and combination of the various parts of my ignition trip whereby the objects contemplated are attained, as hereinafter more fully set ing omitted, this element being shown diagrammatically in Figure4.

Figure 3 is a view similar to a portion of Figure 2, showing certain of the parts in different operating positions, and

Figure 4 is an electro-diagrammatic view of a typical circuit in which my ignition trip may be used.

0n the accompanying drawings I have used the reference numeral III to indicate a panel formed preferably of insulating material. The panel i0 is provided with a bearing l2 in which a rod I4 is rotatably mounted. The rod M as shown diagrammatically in Figure 4 has secured thereto at l6 one end of a bimetal element Hi, the other end of which is secured at 20 to the bearing l2. The bimetal element is adapted to be located in the stack so as to respond to the combustion temperature therein.

An L-shaped lever 22 is mounted on the shaft I4 and is driven frictionally therefrom through the medium of friction discs 24 and 26, the disc 24 being secured to the shaft and the disc 26 being slidably but non-rotatably mounted thereon. The discs 24 and 26 are frictionally engaged with opposite faces of the lever 22 by means of a coil spring 28 interposed between the disc 26 and a third disc 30 secured to the shaft l4.

Mountedon the panel III is a relay coil RC having the usual frame to which a relay armature 32 is pivoted at 33. The armature 32 is adapted to be attracted by the relay coil when energized and will thereupon move to the position shown in Figure 3, the normal position with the relay dropped out being shown in Figure 2.

The relay armature operates a motor switch MB and a holding switch HS, these switches beme in the form of bridging contacts cooperable with stationary contacts 34, 36, 3B and 40 as shown in Figure 4.

A safety switch S8 is mounted on the Panel ill and as shown diagrammatically in Figure 4 comprises a safety switch heater SSH, a bimetal element 42, a latch 44 therefor and a safety switch contact 46.

The particular invention here involved includes the L-shaped arm 22 having two distinct portions 22a and 22!: serving different purposes, and the following described mechanism. Mounted on a stationary bracket 48 i a leaf spring 50 of the shape shown in Figure 2 and terminating at its upper end in an ignition contact If. A latch arm I! is secured to the spring ill and extends toward the armature II.

The armature is provided with a cooperating latch bracket 58 having an opening 58 therein. A stop bracket 60 is provided to predetermine the dormant position of the leaf spring ill as in Figure 2. The contact 52 is adapted to co-act with a stationary contact 54 carried by a bracket 56 extending from the panel Ill.

The contacts 52 and 54 are for controlling the circuit of the ignition transformer for th burner, this being shown diagrammatically as IGN in Figure 4. The motor switch MS and its contacts 34 and 16 control the circuit of the burner motor n M, the burner being shown diagrammatically at B.

A step-down transformer T is provided which supplies low voltage current for a control circuit including a room thermostat RT, the safety switch BS, the relay coil RC, the holding switch HS and a combustion switch CS. The combustion switch CS is normally open due to the resiliency in the leaf spring 61, the combustion switch being closed by the arm 22?: when the thermostat it cools down, and the combustion switch CS controls the flow of current through the safety switch heater SSH as evident upon an inspection of Figure 4.

When the room thermostat RT closes, a circuit will be established through the relay coil RC from the top of the secondary through CS, SSH, 46 and 44. This energizes the relay coil from the entire secondary of the transformer and results in the armature 32 being attracted for closing the motor switch MS and the holding'switch H8 at the same time the bracket 56 engages the left hand end of the latch 53 and moves it toward the right which bends the spring 50 to the position shown in Figure 3 and engages the ignition contact I! with the ignitioncontact I4.

Closure of the motor switch MS energizes the motor M and in conjunction with the contacts 52 and 54 energizes the ignition IGN. Closure of the switch HS connects the left end of the relay coil with a center tap 4| of the transformer secondary which results in the relay coil being maintained energized from the lower half only of the relay coil so that the drop-out voltage is relatively higher than would be the case if the relay coil were maintained energized by the entire transformer secondary. The upper half of the transformer secondary supplies current through the holding switch to the safety switch heater through the combustion switch CS so that combustion is the controlling factor for the safety switch heater after the holding switch closes.

when combustion is successfully established, the combustion switch opens thus de-energizing thesafety switchheatersoasnottowarpthe bimetal element 42 to the lock-out position, and thereafter as long as the room thermostat calls for heat, the relay coil will be maintained energized by the lower half of the secondary. When the room thermostat is satisfied, the relay coil circuit is broken and the relay accordingly drops out, the latch 56 moving out to the initial position of Figure 2. which removes the opening it with respect to the latch it and permits it to spring up from the dotted position of Figure 3 to the full line position of Figure 2.

At the same time that the combustion switch is permitted to open due to counter-clockwise rotation of the lever 22 in Figure 4, the arm 22a of this lever engages the latch is as indicated by the arrow 0 in Figure 3 to cause it to be lowered so that its left end will enter the opening it and the resiliency of the spring It willmove the latch in the direction of the arrow b to the dotted position shown in this figure. This disengages the contact 52 from the contact 54 for breakin the circuit to the ignition mechanism.

In the event that combustion is not successfully established the safety switch heater will continue to remain in the circuit and warp the bimetal element 42 upwardly to a position that releases the arm 44 and permits it to be separated from the contact 46 by the action of the spring 45. A stop is shown at 41 to limit the movement of the arm 44 by the spring 45.

From the foregoing specification it will be obvious that I have provided a simple mechanical means to release the ignition switch in the event of combustion establishment without the necessity of providing the latching arrangement, an

ignition trip coil, a circuit therefor and contacts for this circuit as in the Shaw patent. The mechanism is simple to fabricate and reliable in operation and accomplishes all the results of the Shaw invention with a structure that is less expensive to manufacture.

Some changes may be made in the construction and arrangement of the parts of my ignition trip without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

I claim as my invention:

1. In a relay structure, a relay coil, an armature for attraction thereby when said relay coil is energized, normally open main contacts adapted to be closed by said armature when said relay coil is energized, secondary contacts normally biased to open position, and means for actuating said secondary contacts comprising a latch operatively connected therewith to close them when the latch is moved in one direction, said armature having a projection to engage said latch when said armature moves in response to energization of said relay coil to effect such movement, said projection having an opening spaced from the point of engagement of the projection with said latch, and temperature responsive means movable on temperature riseto engage said latch and move the portion thereof engaged by said projection to a position of alignment with said opening whereupon the bias for said secondary contacts moves said latch through said opening and opens said secondary contacts.

2. In a relay structure, a relay coil, an armature for attraction thereby when said relay coil is energized, normally open main contacts adapted to be closed by said armature when said relay coil is energized, secondary contacts normally biased to open position, and means for actuating said secondary contacts comprising a latch operatively connected with said secondary contacts to close them when the latch is moved in one direction, said armature having a projection to engage said latch when said armature moves in response to energization of said relay coil to effect such movement, said projection having an opening spaced from the point of engagement of the projection with said latch, temperature responsive means movable upon temperature rise to engage said latch and move the portion thereof engaged by said projection to a position of alignment with said opening whereupon the bias for said secondary contacts moves said latch through said opening and opens said secondary contacts, said armature upon returning to nor- 6 mal position as a result of de-energization of said relay coil moving said opening from engagement with said latch, and means biasing said latch to a position of alignment with said portion of said projection to restore the latch to operative position for the next cycle of operation beginning with re-energization of said relay coil.

PAUL SCHELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,162,126 Shaw June 13, 1929 2,237,120 Soderholm Apr. 1, 1941 

